Study selection

Trials were selected if they included adults or children; evaluations of real-time
ultrasonography or real-time Doppler ultrasonographic guidance for central venous
catheter placement; and measures of success and rapidity of placement, complication
rate, and rate of success after failure by an alternate method. Patients included
were adults in the intensive care unit who were critically ill; had cardiothoracic,
cardiac, or cardiovascular surgery; received a mixture of medical and surgical or
low-risk medical and surgical treatment; and were obese or had coagulopathy. Operators
consisted of 2 consultant anesthetists, residents, anesthesia staff, junior housestaff,
18 operators who had done < 30 procedures, and operators with a mean of 6 years
of experience.

Data extraction

Data were extracted on patient numbers and characteristics; method of insertion; method
of randomization; site of entry; number and experience of operators; method of ultrasonographic
guidance; and speed, success, complications, and number of catheter placements.

Commentary

Central venous catheterization is an essential skill for many physicians. Despite
the potential for serious complications, the procedure is generally safe and successful.
The use of ultrasonographic guidance is not widely practiced compared with the traditional
anatomical landmark method. All the devices examined in this review use ultrasonography
but involve various techniques. For example, 1 device consists of a probe placed through
the cannulating needle connected to a speaker-containing instrument, whereas others
consist of a cutaneous transducer and video screen. The former guides the operator
by characteristic Doppler sounds, and the latter provides a 2-dimensional image of
underlying anatomy. Safe use of these devices requires additional training beyond
proficiency with landmark methods. All entail added expense for the instrument, associated
supplies, maintenance, and training.

This review shows that ultrasonographic guidance improves the rate of successful cannulation.
An intuitive alternative to routine use would be to use guidance only if the landmark
method fails, in high-risk patients, or in patients for whom difficult cannulation
is anticipated. An even more important finding is that ultrasonographic guidance is
associated with lower complication rates. The authors show that these guidance methods
can, on average, spare 1 complication in 7 patients. The actual effect on patient
care is more elusive because many complications, such as most arterial punctures and
catheter malpositions, do not cause important adverse consequences. Large-scale studies
that examine actual morbidity and costs are necessary to determine the real cost-effectiveness
of the technique.

For both the landmark and ultrasonography-guided methods, training and experience
are required to master and maintain proficiency. If routine use of some of these techniques
becomes the norm, what effect would this have for future operators who receive all
or most of their training using real-time guidance? Perhaps lack of experience with
landmark methods would render them less adroit in emergency or other situations in
which catheterization is necessary but ultrasonography instruments are unavailable.